When ever the subject of "the best oil" comes up usually everyone has a different opinion. Personally I have to rely on experience and the results I have seen in engine teardowns. Some vital factors people are generally unaware of is how EPA regulation has forced changes in oil formulation that can be catastrophic results for certain engines. Modern "energy conserving oils" are DEATH for older engines with flat tappet lifters. Especially if the engine is modded with heavy valve springs and a performance cam. Energy conserving oil do not have the Zinc Phosphate that is the key to engine protection. The zinc is "the goods" that actually give your engine a long life. I have seen freshly built; low mileage engine with wiped out cam lobes because of this oil.You are MUCH better off with a diesel oil in older flat tappet engines. I run Shell Rotella in my older stuff. It is an excellent oil and diesel engine oil still contains a good amount of Zinc Phosphate. Modern engines with roller cams; I can't recommend anything other than Mobil1. Take a look at this page (mine); it details the tear down of a 3rd gen Hemi because of a rod failure. It was NOT a maintenance or oil issue. The cause was a failed rod because of poor metallurgy. You can see after 130k+ miles the internals for engine are like new. The lack of wear was simply amazing. CLICK HERE

I have had similiar luck with Sythetics like Mobil 1. I had a turbo Shelby that went for 130K before I sold it. Took the head off once to change the gasket and the engine looked like brand new inside. No browning of the metal surfaces, the cylinder walls still had the hone marks on them. I was sold. I never put anything else in my vehicles since and I have never had an engine failure.

With the exception of my 55 Chrysler Poly. I have been worried about the zinc issue but the performance of the Mobil 1 has me wondering why wouldn't this oil work in the 55 Chrysler? It has excellent characteristics, lasts twice as long as normal oil, (you only change it because it's dirty not because it is ineffective at lubrication). Why wouldn't it be just as effective in an older engine without the Zinc additive?

Beltran wrote:I have had similiar luck with Sythetics like Mobil 1. I had a turbo Shelby that went for 130K before I sold it. Took the head off once to change the gasket and the engine looked like brand new inside. No browning of the metal surfaces, the cylinder walls still had the hone marks on them. I was sold. I never put anything else in my vehicles since and I have never had an engine failure.

With the exception of my 55 Chrysler Poly. I have been worried about the zinc issue but the performance of the Mobil 1 has me wondering why wouldn't this oil work in the 55 Chrysler? It has excellent characteristics, lasts twice as long as normal oil, (you only change it because it's dirty not because it is ineffective at lubrication). Why wouldn't it be just as effective in an older engine without the Zinc additive?

The ZDDP in nonroller motors may be real, might not be. There was a rash of cam failures in BB Chevys with high pressure valve springs a while back. Cams seemed to have come from one Company. Maybe bad cams, or bad Chinese lifters, maybe no ZDDP. Can't really say for sure. Supposedly the ZDDP was replaced with good substitute, but Shell Oil suggests diesel oil for older engines, where SM has 0 ZDDP. The Accel brand SF 10W-40 oil has been dropped by Wal-Mart, but is available @ Fastenal, NAPA & soon @ Amazon. Your 80s shelby is a roller engine, doesn't need ZDDP>